The present disclosure relates to a calibrating apparatus which is adapted to remove a measurement deviation of a pyrometer, and more particularly, to an apparatus for calibrating a pyrometer, which calibrates a reference value so as to remove a deviation in a temperature measured in a non-contact manner.
In a heat treatment apparatus which performs a heat treatment process with respect to a substrate, heat is supplied to a silicon substrate using a heating lamp such as a halogen lamp, and a temperature of the substrate is measured through an optical probe, and the measured temperature of the substrate is fed back to a heating controller so as to control the heating lamp.
FIG. 1 is a schematic view illustrating a low temperature heat treatment apparatus. As illustrated in FIG. 1, in a state in which a substrate 20 is installed at an edge ring 30 in a process chamber 10, a heat treatment is carried out by a plurality of heating lamps 61, and a temperature of the substrate 20 is measured by a low temperature measuring pyrometer 40 in a non-contact manner. That is, the temperature measuring pyrometer 40 serves to concentrate a radiant energy intensity of approximately 5 μm to approximately 20 μm, which has a low temperature of approximately 600° C. or less and is radiated from the substrate 20, through a lens 41 and then calculate the temperature of the substrate in the non-contact manner, based on blackbody radiation temperature relationship. The temperature calculated by the temperature measuring pyrometer 40 is fed back to a heating part 60 through a heating controller 50 so as to control temperature of the plurality of heating lamp 61.
Meanwhile, when the temperature measuring pyrometer 40 is assembled to the heat treatment apparatus for the first time, a reference vale of the temperature measuring pyrometer 40 should be calibrated in order to calculate a correct temperature when the temperature measuring pyrometer 40 is exposed to the radiant energy from the heated substrate. Further, when the temperature measuring pyrometer 40 is used for a long time, the temperature detected by the temperature measuring pyrometer 40 may not be correct, and it is necessary to periodically re-calibrate the temperature measuring pyrometer 40. For example, when an area through which light radiated from the substrate during heating of the substrate passes is contaminated, the measured temperature may not be correct, and thus a corresponding re-calibration operation is needed.
The calibration of the reference value with respect to the temperature measuring pyrometer is performed through a deviation correction of approximately ±1 by a calibrating apparatus using a blackbody.
FIG. 2 is a view illustrating a state in which a calibrating apparatus is in contact with a temperature measuring pyrometer in order to calibrate the temperature measuring pyrometer using the calibrating apparatus. The calibrating apparatus 1 has a blackbody 110 therein, and radiant energy radiated from a radiant space S in the blackbody 110 is released through a light output port to an outside. Therefore, the radiant energy released through the light output port to the outside may be transmitted to a lens 41 provided at the temperature measuring pyrometer 40 arranged at the light output port. Therefore, when the blackbody 110 in the calibrating apparatus is set to a certain temperature, e.g., approximately 600° C., the corresponding radiant energy is transmitted to the temperature measuring pyrometer 40, and a temperature correction of the temperature measuring pyrometer 40 is performed to correspond to the temperature of the blackbody 110, i.e., approximately 600° C. For example, if a temperature calculated by the temperature measuring pyrometer 40 is approximately 598° C. in a situation in which the radiant energy of approximately 600° C. is actually released from the radiant space S of the blackbody 110, the reference value used for calculating the temperature in the temperature measuring pyrometer 40 is calibrated to correspond to the temperature of approximately 600° C.
Meanwhile, the calibrating apparatus 1 has to increase the temperature of the blackbody 110 disposed therein to a desired certain temperature (e.g., approximately 600° C.) before performing a temperature correction operation. However, according to a test result, in case of a conventional calibrating apparatus, when the temperature of the blackbody 110 is increased to the desired high temperature, it takes too much time. This is because heat exchange with an outside of the blackbody hardly occurs due to a small size of the light output port.
Further, if the light output port is blocked by a transparent blocking plate (not shown) in order to prevent introduction of foreign substances, the temperature of the blackbody 110 is more slowly increased due to a blocking effect of the transparent blocking plate. When the light output port is opened without the transparent blocking plate, the temperature of the blackbody 110 is increased at least slowly, but when the transparent blocking plate is provided so that the radiant space S of the blackbody 110 is completely sealed, the temperature of the blackbody 110 is increased hardly.
This is because an inside of the calibrating apparatus 1 is completely isolated from an outside thereof by the transparent blocking plate and thus a convection current is not generated, whereby it is difficult to rapidly increase the temperature of the blackbody 110. That is, since the blackbody 110 has an insulation effect due to the isolation from the outside, the temperature of the blackbody 110 is not changed rapidly.
Furthermore, this is because the transparent blocking plate is made of quartz or sapphire which does not transmit long wavelength energy having a low temperature of approximately 600° C. or less.